Paper and cardboard comprising starch- and protein-containing material

ABSTRACT

Paper and cardboard containing starch and protein fractions of flour having improved strength, stiffness and surface properties, wherein the starch and protein fractions are subjected to a degradation with ammonium persulfate, amylase, an acid, protease or a combination thereof before being introduced to the paper or cardboard. After the starch and protein fractions have been degraded, they can be added to the paper fiber matrix or used as a sizing or glue.

The invention resides in the field of paper and cardboard manufacturing.In particular, the invention relates to the use of a combination ofstarch- and protein-containing material in paper and cardboard. In fact,in this specification and the claims, the term `paper` is meant toinclude cardboard as well.

Traditionally, starches are used on a large scale and in large volumesin the paper and cardboard industry. In the production of coated paper,which is substantially used as graphic paper in the fine-paper industry,it is used as, inter alia, binding agent in the coating. In general,this starch is a modified starch.

In addition, starch is used as admixture for improving the strengthproperties, and in particular the dry-strength properties, of the paper.For that purpose, starches conventionally used in the paper industry andanionic and cationic derivatives of these starches are used, for whichreference can be made to, for instance, EP-A-0 545 228 andWO-A-94/05855.

In this connection, further reference can be made to Kirk-Othmer,Encyclopedia of Chemical Technology, Third Edition (1981), John Wiley &Sons, Volume 16, p. 803 ff, in particular pp. 814-819.

In the most current uses of starch as fiber-reinforcing component, it iseither introduced--usually in the form of cationic starch--into the massof the paper in the wet portion of the paper process, orimpregnated--substantially in the form of solubilized nativestarch--into the paper fiber mass by means of the so-called size press.

These known strength-improving additives are advantageous, both in aneconomical and in a technical or technological sense; they give thepaper or the cardboard an added value. Apart from providing an addedvalue in conventional paper and cardboard processes, the need foradditives for increasing the strength is enhanced in particular by theincreasing use of weaker fibers, old paper that is reused more and moreoften, and a further increasing use of fillers instead of fibers in thisold paper, resulting in a decreasing strength potential, and thedecreasing availability of strong, long-fiber components in the basepulp for paper.

Actually, it is now emphasized that the invention is not limited to"waste-based" paper. The invention extends across the entire area ofpaper and cardboard manufacture, including paper based on "virginfiber".

The known starch-based additives can enter into large-scale interactionswith the cellulose groups of paper fibers. Thus, an increase of thenumber of bonds between the mutual paper fibers is formed, whichreinforces the fiber-fiber bond and, accordingly, improves the strengthproperties of the final product.

In conventional processes wherein starches are used as strengthener,strict requirements are imposed on the protein content that may bepresent in the starch product used. In particular, native starch usedfor the manufacture of paper, substantially native wheat-, corn- orpotato starch, is supplied with an additional specification for maximumprotein contents of 0.3-0.5 wt. %, calculated on the dry substance.Higher protein contents are supposed to have a contaminating effect andto cause lump formation and depositions in the system. For instance, thedispersion of gluten (the protein fraction in wheat flour) leads tolumping and foam formation. These drawbacks occur to an enlarged extentwhen these proteins are exposed to higher temperatures in the papermanufacturing process.

The starch which forms the basic material for presently used starchadditives in paper is recovered from a large number of vegetablesources, for instance from grains, such as wheat, corn and rice; fromtubers, such as potatoes and tapioca; or from other plant parts, such assago.

From the above-mentioned vegetable sources, the starch is released bythe use of a combination of mechanical steps, purifying steps and dryingsteps. The separated protein-containing fractions, as well as otherby-product fractions, are discharged. The starch purification involvesthe release of many waste flows, such as water flows containingbiological material. These flows are increasingly becoming anenvironmental problem, so that draining without more is no longerpossible.

The preparation of the starch that is used in the paper industry in thelargest amounts as fiber-reinforcing and paper-stiffening agent, viz.wheat starch, is described as example. Similar processes are carried outfor rendering starch from other vegetable sources applicable to thepaper industry.

Wheat grains substantially consist of two components. The core, theso-called endosperm, largely consists of starch and protein. The outerlayer, the brans or the chaff, mainly contains cellulose. The ratiocore:outer layer is about 80:20.

These wheat grains are ground, the chaff being separated from the core.The separated endosperm, consisting for about 70-80% of starch and forabout 10-15% of protein, is commonly designated by the term "flour".Depending on the extraction degree of the wheat, more or less pure flouris obtained. For instance, at an extraction degree of about 80%, "greyflour" is obtained, while at a somewhat lower extraction degree of about70%, considerably purer flour is obtained, because at this extractiondegree, no parts other than the endosperm end up in the flour.

In the production of starch for the paper industry, the protein, inparticular the gluten, is subsequently washed from the flour. The flouris thus separated into two main components. As indicated, in thisprocess, economically unprofitable drying steps are carried out, a partof the starting substance wheat cannot be used, and waste flows arecreated that have to be processed.

The primary object of the present invention is to provide a methodwherein an optimized use is made of raw materials in the sense that alargest possible fraction of the raw material can be used in the paperprocess.

This object is realized by introducing the components of flour into themanufacturing process of paper or cardboard completely, without thisflour or flour components being priorly modified by binding cationic oranionic groups thereto or without such protein/starch mixtures beingpriorly dry-modified. In other words, the object is realized by startingfrom native protein/starch mixtures and using them as such. In thisspecification and claims, by "flour" is meant a protein- andstarch-containing fraction originating from one and the same vegetablesource, or a natural mixture of protein and starch.

More in particular, the invention relates to paper or cardboardcomprising the components of native flour in the paper fiber matrix. Inaddition, the invention relates to a method for manufacturing paper orcardboard wherein flour is substantially subjected to a treatmentwhereby starch and protein are solubilized, after which the treatedcomponents of flour are jointly introduced into the paper fiber matrixin one step. Moreover, the invention relates to a method whereinvegetable starch sources can be used entirely, hence without generatingwaste products, in the paper industry.

Accordingly, the invention relates to paper of cardboard comprisingprotein and starch, at least partly originating from the same source, inthe paper fiber matrix. Further, the invention relates to paper orcardboard into which all components from vegetable starch/proteinsources have been processed.

It has been found that by the use of an amount of flour according to theinvention, paper can be obtained which has substantially the sameproperties as paper wherein about the same amount of starch is used. Inother words, the function of a part of the conventionally requiredstarch can be taken over by the protein fraction in flour, although theprior art merely teaches disadvantageous properties. In addition toeconomical advantages--flour is cheaper than starch preparedtherefrom--, technological and environmental advantages are obtained aswell, because no drying steps or purifying steps have to be carried out,and/or because no waste flows have to be discharged.

The paper according to the invention preferably comprises at least 0.1wt. %, more preferably at least 0.3 wt. %, and usually 0.3-8 wt. %starch and at least 0.03 wt. %, preferably between 0.05 wt. % and 2.4wt. %, usually 0.05-1 wt. % protein in the paper fiber matrix,calculcated on the weight of the dry substance. If less than the minimumcontents of protein and starch are used, the advantages obtainedaccording to the present invention are too slight or other conventionalauxiliary substances are required for obtaining the desired paperproperties. It is true that if more than 8 wt. % starch and more than 1wt. % protein is used, paper of a very high added value is obtained, butfrom a business-economical viewpoint, the process is often lessattractive.

Preferably, 2-5 wt. % starch in addition to 0.2-1 wt. % protein isintroduced into the paper fiber matrix, because this combines theadvantages of the invention with a favorable production price.

In accordance with the present invention, the protein and starchfraction at least partly originates from one and the same vegetablesource. As vegetable sources that can be used for this purpose, thosehaving a high content of starch next to protein can be mentioned, forinstance seeds, such as beans, peas and grains, for instance wheat, cornand rice grains; and other protein- and high starch-containing plantparts. In the present specification and claims, these products aredesignated by the term "flour".

Preferably, flour originating from grains or pulses, preferably wheatflour, is introduced into the fiber mass of the paper or cardboard. Agreat advantage of the use of flour originating from grains and pulsesis that from an economical viewpoint, for use in accordance with thepresent invention, this raw material is more attractive than the starchthat is normally used. For instance, at this moment, the cost of wheatflour are about half the cost of native wheat starch.

Further, because of the omission of the separation of flour into astarch and protein component, the energy consumption is reducedconsiderably, partly because no drying steps have to be carried out.

Flour originating from grains or pulses, and in particular wheat flour,is used in amounts of preferably 2-5% calculated on the dry mass.

Wheat flour cannot be introduced into the paper as such. If this isattempted, the drawbacks known from the prior art--high degree ofdeposition, lumping, dough formation, foam formation--occur. Theproblems prove not to occur when the flour is at least subjected to atreatment known for native starch in the paper industry.

As a skilled person knows, for use on the size press, a productdissolved in water and having a Brookfield viscosity of less than about100 cP is required. Such a solution (it is suitable to start from a 10wt. % flour suspension) can be obtained by treating wheat flour with achemical and/or enzymatic starch chain-degrading agent to obtain aviscosity in the above-mentioned range. For instance, flour can besubjected to a degradation with ammonium persulfate (APS), known fornative starch, optionally in the presence of an acid, for instanceacetic acid or citric acid. The presence of acid in this embodiment isfor instance needed if wheat flour is started from, which is illustratedin Example 2. Other methods are treatments with amylases or combinationsthereof with APS, optionally complemented with a protein-modifying step.

Whereas for an interference-free size press treatment, the viscosity ofnative starch solutions known from the prior art is preferably betweenabout 30 and 80 cP, a viscosity as low as only 15 cP is sufficient whenflour is used. From Example 1 below, it appears that this produces apaper of the same quality as in the case where only starch is used.

In fact, it is also possible to eliminate interfering properties causedby the protein component in flour by substantially degrading thisprotein component and, accordingly, only utilizing the starch componenteffectively.

However, this embodiment lacks a number of the advantages of the presentinvention.

Dutch patent application 1001218 describes that proteins can improve thestrength properties of paper and cardboard and, in addition, have alarge number of advantages when they are present in the paper fibermatrix. In particular, proteins inter alia provide, apart from improvedstiffness values, SCT--("Shortspan Compression Test"), RCT--("Ring CrushTest"), and CMT--("Concora Medium Test") values--and strengthvalues--inter alia burst pressure, tensile strength--, which values area measure for specific strength properties of the paper, in particularfor the production of corrugated board, optimization possibilities andimprovements in other constructional paper properties, such asstiffness, in properties of processability, such as foldability andscoring facility, and in functional properties, such as permeability togases and liquids. Moreover, the use of proteins in paper manufacturingprovides optimization possibilities and improvements in the field ofgeneral process control, usability of raw and auxiliary materials, andenergy demand. Further, the above-mentioned properties can be controlleddepending on the manufacturing conditions and conditions of application,for instance climatological conditions, without this being at theexpense of the reprocessability of the paper product and the output ofthe production process.

In accordance with the present invention, it has now been found that theadvantages mentioned in Dutch patent application 1001218 can also beobtained by the use of flour components in paper. For that purpose, notonly the one-step treatment as known for native starch should be carriedout, but a second treatment should be carried out as well. For the useof wheat flour with the size press, this second treatment is adeamidation reaction and/or a partial proteolysis. This second treatmentrenders the wheat gluten more water-soluble and can be carried out in athermo-chemical manner (warming by acid) as well as in an enzymaticmanner (protease).

In a preferred embodiment, the wheat flour is treated with acid APS at atemperature of about 85-95° C. In addition to the degradation of thestarch, this treatment provides at the same time a processing of theprotein.

As appears from the examples given below, synergistic effects occur whena starch/protein mixture prepared in an unseparated manner is used inconformity with the invention. The effect of flour on the strength andstiffness properties of paper is as great as and sometimes even greaterthan the effect of an approximately equally large weight fraction ofconventionally treated and used, native starch.

It has been demonstrated that by introducing protein and starchmolecules into the paper fiber matrix, in particular the stiffness andstrength properties can be positively modified and controllablyinfluenced.

These paper properties are not only important in respect of wrappingpapers based on recirculated material, but also in respect of solidcardboard and various types of paper based on "virgin fiber".

For obtaining a good paper product, it is essential that the proteinand/or starch molecules be present in the paper sheet. After all, theoptimization of the fiber-fiber bond of the paper, whereby the resultingadvantages can--probably--be explained, can only take place whensufficient protein and/or starch material is present on, in and betweenthe fibers. In this manner, the paper fiber mass and the protein andstarch fraction form a whole; no clearly sharply delimited protein andstarch masses and paper fiber masses are distinguished.

The advantageous effects of the use of protein in combination withstarch in the bulk of the paper are dependent, sometimes even to a highdegree, on the place or manner of applying and/or the nature of theprotein introduced. After taking cognizance of the specification of thepresent invention, it will be within the scope of a skilled person toadjust the paper-manufacturing process, including the raw and auxiliarymaterials to be used, depending on the wishes of the customer/user andthe conditions.

These above-mentioned flour-processing methods generally and mainlybring the protein fraction into solution, while the starch issolubilized and degraded. The treatment of the flour can be carried outbatchwise as well as continuously-in-line.

The invention further relates to a method for manufacturing paper orcardboard, comprising at least a step wherein proteins and starch, i.e.the product as it is recovered from a natural product as unseparatedvegetable protein/starch mixture, optionally after being subjected tothe above-elaborated treatment analogously with the treatment carriedout with native starch, is introduced into the paper fiber matrix.

In conventional paper-manufacturing processes the first treatmentconsists in so-called pulping--preparing pulp by suspending fibermaterials in paper that may or may not have been circulated. In a largevat, by the use of mechanical energy, usually by stirring, and heating,usually with steam or warm water, fiber material is added to water.Through the mechanical and physical treatment, the fiber material isdissolved or dispersed to create a liquid mash, the pulp. Next, the pulpis subjected to a number of treatments. For instance, the pulp iscleaned, with unusable, nonfibrous material being removed from the pulp.Moreover, if necessary, a fiber treatment, such a grinding, is carriedout. Finally, the pulp is presented in a specific concentration to thepaper machine which manufactures paper from the pulp.

In accordance with the invention, during the method for manufacturingpaper, at least a step is carried out whereby proteins and starch arejointly introduced into the paper fiber matrix.

During the process pass from pulp vat to paper machine, auxiliarysubstances, including the protein-starch mixture used according to thepresent invention, preferably wheat flour, can be added. Moreover, aftersheet formation, the protein and starch material can be provided thereonand then--by performing specific treatments--introduced into the fibermatrix.

For instance, during the paper sheet formation, protein-starch solutionscan be introduced into the paper layer or between different paperlayers, if any, for instance through spraying or foaming. Also, theprotein-starch material can be introduced into the fiber mass by meansof a surface treatment or impregnation of the paper already formed, forinstance and preferably by means of a size press treatment. Finally,reference is made to the possibility of applying protein material to thedry paper web through spraying or other known application techniques.

In a preferred embodiment of the method according to the invention,protein-starch mixtures are introduced into the paper by means of a sizepress treatment. During the size press treatment--a treatment which isgenerally used in the paper industry and is therefore known to a skilledperson--a solution or suspension containing the protein-starch mixtureto be used is pressed into the paper by means of rolling. The size presstreatment can be carried out single-sidedly on the top or bottom side ofthe paper web, as well as double-sidedly.

In particular for use in the size press, higher protein and starchconcentrations have advantages with regard to the maximally feasibleproperties and reduced drying energy thus required.

In the above-mentioned techniques, it is always important that at leasta part of the proteins and the starch be brought into close contact withthe fibers in the paper fiber matrix.

Further, it is possible to introduce, in addition to the jointintroduction of a protein/starch mixture, supplementary amounts ofstarch or protein. This can take place at the same place by the use ofthe same technique, but also at other places in the paper-preparingprocess.

The invention relates to the use of flour components in the fiber matrixof paper for improving and directing paper properties such as strength,stiffness, permeability, surface properties and elasticity. Moreover,the flour fraction treated according to the invention can be used asglue for fixing the corrugations in corrugated cardboard.

The invention also relates to the use of protein- and starch-containingmaterials wherein, for attaining the desired paper properties, only thestarch fraction is modified chemically or enzymatically. If the startingmaterial contains, in addition to starch, for instance water-solubleproteins, it is not necessary to modify these proteins in order toproduce a size having good processing and reinforcing properties. Anexample hereof is pea meal of which the proteins are soluble in analkaline medium.

Moreover, for reinforcing the paper, it is possible to use only thestarch fraction of starch- and protein-containing materials. On the onehand, this can be effected on account of the fact that the protein,without modification, is water-soluble so that it is either pressedthrough the paper during the paper treatment, or, present in the papermatrix, does not contribute to the paper properties. On the other hand,the protein can be modified too far, as a consequence of which it doesnot contribute to the paper properties either. In the most extreme case,the protein is degraded into amino acids. An advantage hereof is that nosharply delimited processing degree of the protein has to be set, sothat the conversion of starch- and protein-containing material into thesuitable size is not a very critical process.

Finally, the invention relates to a method for manufacturing paperwherein vegetable material having as main components protein and starch,preferably grain, is completely processed, comprising separating thevegetable material into (a) a fraction substantially consisting of thecellulose material and (b) a fraction substantially consisting of theprotein and starch material, feeding fraction (a) to the usual startingpaper fiber mass, for instance during the preparation of pulp, andfeeding fraction (b) in the step wherein fiber-reinforcing additives areintroduced. The fraction fed in the step wherein fiber-reinforcedadditives are introduced is treated in conformity with theabove-described method. In particular, in this aspect of the inventionit is possible to completely grind up a vegetable protein and starchsource, for instance wheat, and to use the ground-up productdirectly--after a modification that is analogous with native starch andoptionally after a modification wherein the protein properties areoptimized--as fiber-reinforcing, quality-improving component, and to usethe residual products, such as the chaff, directly as fiber material.The modification of the flour can consist of a thermochemicalconversion, for instance with APS and/or acid, for instance citric acid,optionally in combination with an enzymatic modification with, forinstance, amylase and/or protease.

Presently, the invention will be specified with reference to thefollowing examples.

EXAMPLE 1

In this example, the effect of the use of flour (IJsvogel-flour, MenebaNederland; moisture content 13.5%; about 10 wt. % gluten and about 89.5wt. % starch calculated on the dry product) was studied. For thatpurpose, suspensions of flour and--for comparison--native starch wereintroduced into paper by means of the size press method.

The solutions of the above-mentioned macromolecules were set at adesired viscosity by subjecting both the starch fraction and the flourfraction to a degradation with ammonium persulfate (95° C.). For aninterference-free size press application, the viscosity of the starchsuspension should be between 30 and 80 cP; good results with the floursuspension are already obtained at a viscosity of only 15 cP.

The macromolecules-containing solutions were introduced into paper(recycled paper; D-Liner; Roermond Papier) by means of a laboratory sizepress (Einlehner, rate 30 m/min, temperature 70° C., pressure 2 bar).

The SCT-value and the burst factor were determined according tostandardized requirements.

The SCT-value is the maximum compression force per width unit that atest strip can undergo under defined conditions until this strip becomesupset. In this example, the SCT-determination was carried outperpendicularly to the machine direction of the paper. The SCT-value isexpressed in kN/m.

The burst factor is determined from a burst pressure measurement. Theburst pressure is the pressure exerted on a piece of paper at the momentwhen the paper cracks. The burst factor (expressed in kPa) is equal tothe burst pressure multiplied by 100 divided by the basic weight (g/m²).

The results are stated in the following table.

                  TABLE 1                                                         ______________________________________                                        Increase of the SCT-value and the burst factor                                relative to the control during the use of flour or starch                             SCT-value (kN/m)                                                                         burst factor (kPa)                                         ______________________________________                                        starch    0.75         48                                                     flour     0.65         42                                                     ______________________________________                                    

It has been found that the use of flour gives almost the same increasein SCT-value and burst factor as starch. Moreover, a further influencingof the strength properties can be obtained by using a flour suspensionhaving a different viscosity.

EXAMPLE 2

Pretreatments of Flour Slurries

A) Treatment with Neutral APS

A suspension of 694 g IJsvogel-flour in 1306 g water (50° C.) wasstirred in a beaker. 2.16 g APS was added, followed by stirring foranother 30 minutes at 50° C. The resulting solution was diluted to a 10wt. % solution. Heating at 75° C. took place for 30 minutes, after whichthe whole was boiled for another 60 minutes in a water bath.

B) Treatment with Acid APS

A suspension of 232 g IJsvogel-flour in 1309 g water was stirred in abeaker. Citric acid was added to a pH of 4, after which 0.72 g APS wasfed. After that, the mixture was allowed to boil for 60 minutes in awater bath.

C) Treatment with APS and Protease

A suspension of 694 g IJsvogel-flour in 1306 g water (50° C.) wasstirred in a beaker. 1000 μl Neutrase (NovoNordisk) was added, followedby stirring for another 30 minutes at 50° C. The resulting solution wasdiluted into a 10 wt. % solution. 2.16 g APS was added. The whole wasboiled for 60 minutes in a water bath.

D) Treatment with Amylase and Protease

A suspension of 694 g IJsvogel-flour in 1306 g water (50° C.) wasstirred in a beaker. 933 μl Ban α-amylase and 1000 μl Neutrase (bothNovoNordisk) were added, followed by stirring for another 30 minutes at50° C. The resulting solution was diluted to a 10 wt. % solution. For 30minutes the temperature was increased to 75° C. After that, the wholewas boiled in a water bath for another 30 minutes.

Of the four slurries A-D treated, the Brookfield viscosity wasdetermined in cP. The measuring results are shown in the followingtable.

                  TABLE 2                                                         ______________________________________                                                         Brookfield viscosity (cP)                                    ______________________________________                                        A      APS        --       700                                                B      APS        citric acid                                                                            40                                                 C      APS        protease 40                                                 D      α-amylase                                                                          protease 25                                                 ______________________________________                                    

The flour solutions having viscosities lower than 100 cP could readilybe processed on the size press.

EXAMPLE 3

With a flour slurry obtained according to method D in Example 2 and a 10wt. % standard starch slurry, test sheets (Testliner 3 Roermond Papier,160×100 mm) were treated on a laboratory size press (Einlewner, rate 30m/min, temperature 70° C., pressure 2 bar). The impregnated sheets weredried on a drying cylinder at 130° C.

Of these test sheets, the paper properties were determined underconditioned circumstances (23° C., 50% RV) according to standardizedmethods. The measuring data are stated in the following table.

                  TABLE 3                                                         ______________________________________                                        Strength and stiffness properties                                                                              activity                                     paper        starch    flour     rel. to 100%                                 property     (standard)                                                                              (enzymatic)                                                                             starch                                       ______________________________________                                        take-up (%)  3.2       3.2                                                    burst factor 241       273       +13%                                         (kPa)                                                                         breaking     6454      6915       +7%                                         length (m)                                                                    stretch (%)  1.93      2.13      +10%                                         SCT (140 g)  2.46      2.76      +12%                                         (kN/m)                                                                        stiffness    1022      1036       +1%                                         (kNm)                                                                         CMT 30 (140 g) N                                                                           278       284        +2%                                         ______________________________________                                    

In this table, "take-up" is the weight percentage flour/starch relativeto the dry paper.

EXAMPLE 4

Use of Pea Meal

The proteins in pea meal are water-soluble. From pea meal, a flour sizeis made by modifying only the starch. In a number of experiments, thestarch in pea meal is degraded by means of APS or enzymes.

                  TABLE 4                                                         ______________________________________                                                     size viscosity                                                   treatment    (cP)      SCT-value (kN/m)                                       ______________________________________                                        APS          150       riot determined                                        APS + citric 30        4.2                                                    acid                                                                          BAN          80        4.2                                                    Termamyl     60        4.4                                                    ______________________________________                                    

If a suspension of pea meal is only treated with APS, the suspensionobtains a high viscosity, as a consequence of which the size isdifficult to apply to paper. By reducing the pH of the suspension withcitric acid, the APS becomes more effective, so that a size is obtainedthat does meet the Theological requirements. When this size is appliedto paper, the SCT-value is increased. Also the enzyme BAN and Termamyldegrade the starch sufficiently in a suspension of pea meal to obtain aviscosity lower than 100 cP. During application to paper, the SCT-valueis increased.

EXAMPLE 5

Test on Production Scale

In a test reactor, a four slurry with enzymes (Neutrase) was suspended.Next, this slurry was thermochemically gelatinized with ammoniumpersulfate over a jet-cooker (NEMO-converter). On the paper machine 1(PM1) of Roermond Papier, the flour slurry was processed on the sizepress.

In particular, a practical production run of the quality Testliner 3(RP-Maasliner) in 140 g was carried out.

Machine conditions: standard, i.e.:

composition of raw material according to formulation (recycledmaterial);

2-layer embodiment;

in-line treatment on size press;

weight increase though size press treatment: about 3%;

rate PM: 625 m/min;

final moisture content paper: 7%.

During this paper production, the size press solution of native wheatstarch (thermochemical conversion with ammonium persulfate (APS)) wasreplaced during the run by flour (IJsvogel; conversion: starchthermochemically with APS and protein part enzymatically by means ofNeutrase).

Processing: good. Result comparable with 100% starch.

Paper properties: the paper properties are equal to/comparable withstarch.

Depositions and foam formation resulting from gluten were not observedin the system.

                  TABLE 5                                                         ______________________________________                                        Practical test Maasliner (T.L.3), RP-PM1                                      Paper properties  Starch (standard)                                                                         Flour                                           ______________________________________                                        Gram weight  g/m.sup.2                                                                              140.1       139.9                                       Final moist. cont.                                                                         %        7.1         7.0                                         Take-up      %        3.2         3.1                                         (size press)                                                                  Burst pressure                                                                             kPa      340         335                                         Burst factor kPa      243         239                                         Breaking 1.                                                                             m.d.   m        6,610     6,640                                     Stretch   m.d.   %        1.90      1.90                                      R.C.T.    t.d.   kN/m     1.23      1.18                                      S.C.T.    m.d.   kN/m     4.53      4.65                                      S.C.T.    t.d.   kN/m     2.30      2.49                                      Stiffness m.d.   kN/m     960       940                                       ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        properties stated                                                             Paper property      Unit     Standard                                         ______________________________________                                        1.   Gram weight        g/m.sup.2                                                                              ISO 536                                      2.   Moisture content   %        ISO 287                                      3.   Burst pressure     kPa      ISO 2758                                           ##STR1##          kPa      ISO 2758                                     10.  S.C.T.             kN/m     DIN 54518                                    11.  R.C.T.             kN/m     DIN 53134                                    12.  C.M.T.-30          N        ISO 7263                                     13.  Porosity           ml/min   ISO 5636/3                                        (acc. to Bendtsen)                                                       8.   Stiffness          kN/m     ISO 1924/2                                   5.   Tensile strength   kN/m     ISO 1924/2                                   9.   Tearing strength   mN       ISO 1974                                     14.  Ply-bond           J/m.sup.2                                                                              Tappi UM 403                                      (Scott-Bond)                                                             7.   Stretch            %        ISO 1924/2                                   6.   Breaking length    km       ISO 1924/2                                   ______________________________________                                         Note:                                                                         the determinations according to 5, 6, 7, 8, 9, 10, 11 and 12 can be           performed in the fiber direction of the paper = machine direction (m.d.)      or longitudinal direction (l.d.), or in the transverse direction (t.d.). 

EXAMPLE 6

Example 5 was repeated, the flour slurry with citric acid beingsuspended. The results were comparable with those in Example 5.

We claim:
 1. Paper or cardboard comprising protein and starch componentsof flour in the paper fiber matrix, wherein the components are subjectedto a degradation with ammonium persulfate (APS) and protease, APS andamylase, APS and an acid, or amylase and protease, in order tosolubilize the protein and starch components of the flour, before beingintroduced to the paper or cardboard.
 2. The paper or cardboardaccording to claim 1, wherein the starch component is 0.1-8 wt. % andthe protein component is 0.3-1.4 wt. %, calculated on the weight of thedry paper fiber matrix.
 3. The paper or cardboard according to claim 1,wherein the starch component is 2-5 wt. % and the protein component is0.2-1 wt. %, calculated on the weight of the dry paper fiber matrix. 4.The paper or cardboard according to claim 1, 2 or 3, wherein thecomponents originate from agricultural products.
 5. The paper orcardboard according to claim 1, wherein acid is added to the componentsto effect deamidation of the protein component before the components aresubjected to degradation with ammonium persulfate.
 6. The paper andcardboard according to claim 1, wherein the components are subjected todegradation with protease, ammonium persulfate, and an acid.
 7. Thepaper or cardboard according to claim 1, wherein the components aresubjected to degradation with protease and amylase and then heated. 8.The paper or cardboard according to claim 1, wherein the degradationreduces the viscosity to less than about 100 centipoise.
 9. The methodfor manufacturing paper or cardboard according to claim 1, wherein thedegraded flour is introduced into the paper by a size press method. 10.A method for manufacturing paper or cardboard from a fiber matrix andflour comprising subjecting at least the flour to a deamidation reactionand/or partial proteolysis treatment comprising, mixing the flour withammonium persulfate (APS) and protease, APS and amylase, APS and anacid, or amylase and protease, in order to solubilize the protein andstarch components of the flour, and introducing the treated flour intothe fiber matrix in one step.
 11. The method according to claim 10,wherein the flour is introduced into the paper fiber matrix utilizing asize press.
 12. The method according to claim 11, wherein the flour hasa protein fraction and the protein fraction is rendered water-soluble.13. The method for manufacturing paper or cardboard according to claim10, wherein acid is added to the flour to form an acidic mixture andammonium persulfate is added to the mixture.
 14. The method formanufacturing paper or cardboard according to claim 10, wherein proteaseis added to the flour to form a mixture and ammonium persulfate is addedto the mixture.
 15. The method for manufacturing paper of cardboardaccording to claim 10, wherein protease and amylase are added to theflour and then heated.
 16. The method for manufacturing paper orcardboard according to claim 10, wherein said treatment furthercomprises heating the treated flour prior to introducing it to the fibermatrix.
 17. The method for manufacturing paper or cardboard according toclaim 10, wherein said acid is citric acid or acetic acid.
 18. A methodfor manufacturing paper from a starting paper fiber mass, whereinvegetable material of a high protein and starch content is processedcompletely, comprising separating the vegetable material into (a) afraction substantially consisting of the cellulose material and (b) afraction substantially consisting of the protein and starch material,feeding fraction (a) into the starting paper fiber mass to form a mixedpaper fiber mass, treating fraction (b) with ammonium persulfate (APS)and protease, APS and amylase, APS and an acid, or amylase and protease,in order to solubilize the protein and starch components of the flour,and introducing the treated fraction (b) into the mixed paper fiber massin one step.
 19. Paper or cardboard having improved strength properties,stiffness properties, permeability, surface properties and elasticitycomprising:a paper fiber matrix; and vegetable material having as maincomponents protein and starch;wherein said protein and starch aredegraded with ammonium persulfate (APS) and a proteolytic enzyme, APSand protease, APS and amylase, APS and an acid, or amylase and protease,in order to solubilize the protein and starch components of the flour,before being introduced into the paper fiber matrix.
 20. A glue forforming the corrugation in corrugated cardboard, said gluecomprising:vegetable material having as main components protein andstarch;wherein said protein and starch are degraded with ammoniumpersulfate (APS) and a proteolytic enzyme, APS and protease, APS andamylase, APS and an acid, or amylase and protease, in order tosolubilize the protein and starch components of the flour.